code: def test_stdevs(distr_class, params, serialize_fn) -> None:
      distr = distr_class(**params)
      distr = serialize_fn(distr)
      stddevs = distr.stddev
      distr_name = distr.__class__.__name__
      assert stddevs.shape == test_output[distr_name]["stddev"].shape
      assert np.allclose(
          stddevs.asnumpy(),
          test_output[distr_name]["stddev"].asnumpy(),
          atol=1e-11,
      )
  
file_path: gluonts/test/mx/distribution/test_distribution_methods.py
imports: import mxnet
  import numpy
  import pytest
  from gluonts.core.serde import dump_json, load_json
  from gluonts.mx.distribution import Beta, Binned, Categorical, EmpiricalDistribution, Gamma, Gaussian, GenPareto, Laplace, NegativeBinomial, OneInflatedBeta, Poisson, StudentT, Uniform, ZeroAndOneInflatedBeta, ZeroInflatedBeta
label_desc: Use image node_id 2 for calling a global function with example usage: test_stdevs(distr_class, params, serialize_fn) without return types